Apparatus for drying coated sheet stock



July 3, 1956 J. A. BLACK APPARATUS FOR DRYING COATED SHEET swocx 1951 6 Sheets-Sheet 1 Filed Feb. 14

. a 1N VENTOR 3 Jil .102 12 2 Raul James A. Blacla ATTORNEY July 3, 1956 J. A. BLACK 2,752,696

APPARATUS FOR DRYING COATED SHEET STOCK Filed Feb. 14, 1951 6 Sheets-Sheet 2 2L 4o .37 40 104 .3 ,5; as 4? I ,1 71 48 I ll, 92

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INVENTOR Jizmea' A Black BY M4006 ATTORNEY y 1956 J. A. BLACK 2,752,696

APPARATUS FOR DRYING COATED SHEET STOCK Filed Feb. 14, 1951 6 Sheets-Sheet 3 r v I 75 B a 46 I I 73 I INVENTOR. 52 I I. JamwAiuaczr BY 40 .9 55 finale/M6 July 3, 1956 J. A. BLACK APPARATUS FOR DRYING COATED SHEET STOCK 6 Sheets-Sheet 4 Filed Feb. 14, 1951 Joe!- 105 .106

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July 3, 1956 Filed Feb. 14, 1951 J. A. BLACK APPARATUS FOR DRYING COATED SHEET STOCK 6 Sheets -Sheet s fix I a'4 l' i i I, a I y I 84;

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' u L as u h i United States APPARATUS FOR DRYING CGATED SHEET STGCK James A. Black, Grand Rapids, Mich. Application February 14, 1951, Serial No. 210,241 11 Claims. (Cl. 34-149) The present invention relates to apparatus for drying coated sheet stock and more particularly to such apparatus for drying paper stock coated with paint or ink by the process known as silk-screening.

in moving them from place to place.

The primary objects of the invention are, therefore, to provide a drying (l) hastens the drying process, and (2) utilizes space at greater height than that usually available, in fact all the way to the ceiling or nearly so. Other and more specific objects of the invenapparent from the ensuing description.

Illustrative embodiments of the invention are shown in the accompanying drawings, wherein:

Figure 1 is a view of the new drying apparatus partly in side elevation and partly in vertical section taken on line 11 of Figure 2;

Figure 2 is a horizontal sectional view of the same taken on line 2-2 of Figure 1;

Figure 3 is a fragmentary horizontal sectional view of 2 but with certain stock rack-s omitted in this view to better reveal conveyor mechanism below the racks;

Figure 4 is an enlarged fragmentary horizontal sectional view of certain parts of the apparatus taken on lines 44 of Figures 1 and 5;

Figure 5 is a fragmentary vertical sectional view of the same taken on line 55 of Figure 4;

Figure 6 is a fragmentary horizontal sectional view of parts thereof taken on line 66 of Figure 5;

Figure 7 is a fragmentary vertical sectional view of parts thereof taken on line 77 of Figure 4;

Figure 8 is a fragmentary horizontal sectional view of certain other parts of the apparatus taken on lines 8-8 of Figures 1 and 9;

Figure 9 is a fragmentary vertical sectional view of the same taken on line 9-9 of Figure 8;

Figure 10 is a fragmentary side elevational view of certain parts located slightly to the right of parts shown in Figure 9;

Figure ll is a greatly enlarged fragmentary vertical sectional view taken on line 1111 of Figure 8, and also indicated by the line 11-1l of Figure 13, showing certain curling of the stock.

2,?52,6% Patented July 3,

driving parts of their apparatus in their lowermost positions;

Figure 12 is a sectional view similar to Figure 11 but showing the moving parts in their uppermost positions, the section being indicated by line 1212 of Figure 14;

Figure 13 is a fragmentary vertical sectional view taken on line l3-l3 of Figure 11;

Figure 14 is afragmentary vertical sectional view taken on line 1414 of Figure 12;

Figure 15 is a fragmentary horizontal taken on line 15-15 of Figure 1;

Figure 16 is a view of the apparatus partly in top plan and partly in horizontal section taken on line 16-16 of Figure l; and

Figure 17 is a diagrammatic side elevation of an adaptation of the apparatus wherein the drying time of the sheet stock is increased by apparatus.

Referring now in detail to these drawings, the apparatus as shown in Figure 1 is primarily intended for the drying of paper sheet stock which has been coated by a silk screen stencil machine, but the apparatus is also suitable for drying other coated sheet stock such as plywood, glass, plastic, cardboard, etc. The apparatus is built upon a frame generally designated 20 and comprising suitable vertical and horizontal angle bars and channel bars assembled together in any conventional manner as by rivets or welding to form an upstanding frame of rectangular parallellepiped form. Side and end plates of sheet metal, generally designated 21, are secured to the outside of the frame as by welding and a top plate 21a is also provided so as to form a drying chamber 22, and similar sheet metal plates 23 are secured to this structure to form an air-conditioning chamber 24 communicating with the drying chamber 22 through an opening 25 in the end plate of the drying chamber.

The air-conditioning chamber 24 has in its lower outer end wall an air intake vent 26 in which are mounted adjustable vanes 27 whereby the volume of intaken air may be adjusted. At the opposite outer end of the drying chamber 22 is an exhaust vent 28 having an electric fan or blower 29 installed in the upper end thereof. An electric control switch 30 is mounted on the side of the structure and connected to the exhaust blower 29 and to a source of electric current by suitable electrical connections (not shown), and this switch 30 may be manually operated to regulate the speed of the blower 29 and thus to regulate the speed of the air circulated through the air-conditioning and drying chambers.

Immediately after the intaken air enters the air-conditioning chamber 24 through the vent 26, it passes between heating elements 31 arranged in a vertical series and by this means the air is heated to correct temperature, the temperature of the heating elements 31 being regulated by means of a thermostat 32 associated with the chamber 24- and having suitable electrical connections (not shown). The heating elements are desirably made of laminated Pyrex thermoplate which comprises a Nichrome foil fused between two plates of Pyrex, such construction being preferred because it will not produce any sparking to set ofi an explosion when the chamber 22 is filled with the explosive fumes of lacquer or the like.

The heated air passes upwardly between jets of water sectional view having suitable connections (not shown) with a water supply. It is important in the drying of flexible sheet stock such as paper that the proper humidity be maintained within the drying chamber 22 so as to prevent If it is found desirable to intromultiplying certain parts of the duce chemicals into the air circulated through the chamher, this may be done by combining the desired chemicals with the vapor emitted from the conduits 33.

The circulated air next passes upwardly through a series of bafiies which remove any droplets and serve generally to mix the conditioned air to a condition of uniformity, and thence the air is directed by vanes 36 through the opening 25 and into the drying chamber wherein the sheet stock is being circulated by the apparatus hereinafter described.

Spaced vertical guides of channel bar construction are secured to the frame 20 of the apparatus at opposite sides of the drying chamber 22 and arranged so as to provide a'pair of opposite parallel downbeat guides 37 and a pair of opposite parallel upbeat guides 38, both pairs of guides extending from near the top to near the bottom of the chamber 22. A plurality of sheet-carrying racks generally designated 39 are provided with pairs of rollers 40 on opposite sides thereof which are adapted to travel along the front and the downbeat and upbeat :guides and thus the racks 39 may descend on the downbeat guides 37 and ascend on the upbeat guides 33. The racks 39 are thus disposed in a downbeat column and an upbeat column extending from top to bottom of the guides with the rollers 40 of each rack resting on the rollers 40 of the rack immediately therebelow. The up and down directions of movement of the upbeat and downbeat columns are indicated by arrows in Figure 1. Each rack 39 comprises a plurality of spaced slats 41 (see Figure 2) mounted on transverse bars 42, 43 on the outer ends of which bars are secured the rollers 40. The spacing of the slats 431 permits the air within the chamber 22 to circulate therebetween.

A lower horizontal conveyor (see Figure 3) is provided for transferring the racks 39 from beneath the downbeat guides to a position beneath the upbeat guides. This lower conveyor consists -of two conveyor sections, the first section comprising spaced parallel sprocket chains 44 passing over sprocket wheels 45 and 46 on shafts 47 and 43 respectively, and the second section comprising spaced parallel sprocket chains '50 passing over sprocket wheels 51 and 52 on shafts 53 and 54 respectively. The shafts 47, 48, 53 and 54 have their opposite ends turnably mounted in parallel bars '55. Power for turning the sprocket wheels to move the lower conveyor chains is taken off a main drive shaft 56 and is relayed as follows: from the main drive shaft 56 through sprocket chains 57 to shaft 47 and through chains 44 to shaft 48, thence through chains 58 to shaft 54 and through chains 5-19 to shaft 53, all as best'shown in Figure 3. The conveyor chains 44 and have spaced lugs thereon, designated 59 and 60 respectively, which lugs engage spaced depending fingers 61 on opposite sides of the racks 39 so that the racks are carried by 'the'ohains -44 to a pause station indicated at 62 on the parallel bars '55, and from said pause station 62 to a position beneath the upbeat guides 38. The purpose of the pause in the lower conveyor is to provide an interval of time for the upbeat driving means hereinafter described to return from its uppermost to its lowermost position. i

An upper horizontal conveyor is provided for transferring the racks 39 from the top of the upbeat guides 38 to the top of the downbeat guides 37, and the racks 39 are thus moved circuitously in the drying chamber 22. The upper conveyor comprises sprocket chains 63 (see Figures 1 and 16) passing over sprocket wheels 64 and 65 onshafts 66 and 67 respectively, andthe-shaft 67 is turned to move 'the chains 63 by means of other chains 68 which 'operatively connect the sl1aft'67 with the main drive shaft 56. The chains 63 have lugs69 thereon which engage spaced up'standing'fingers 70 on the racks 39 to thus move-theraelrs from'the top of'thc upbeat guides to the top of "the-downbeat guides.

Escapement means are provided at'the bottom of the rear tracks respectively of 9 downbeat guides 37 for intermittently permitting the lowermost rack 39 on the downbeat guides to descend onto the lower conveyor while at the same time supporting the column of racks on the downbeat guides. These escapement means, best shown in Figures 4 through 7, are of the so-called Geneva movement type. A pair of U-shaped brackets 71 is mounted on the frame 26 adjacent the bottom of each downbeat guide (see Figures 4, 5 and 7) and adjacent the front and rear rollers 40 respectively of the lowermost rack on the downbeat guides. These brackets 71 carry shafts 72 on which are mounted Geneva or star wheels 73 which engage the rollers of the lowermost rack to support said rack and the column of racks thereabove. Escapement discs 74 mounted on shafts '75 carried by the brackets 71 mesh with the Geneva wheels to prevent turning movement thereof except when the discs 74 are turned so as to present their arcuate voids 76 to the Geneva wheels, at which time the Geneva wheels are turned to permit descent of the lowermost rack. Turning movement of the Geneva wheels is effected by the engagement of a pin 77 on each escapement disc with one or another of the slots 7-8 in the adjacent Geneva wheel, the disc and wheel turning in the directions indicated by 'arrows (Figure 5.).

Stationary downbeat bases 79 having tracks '80'thereon receive the lowermost rack when it is permitted to descend from the downbeat guides by the escapement mechanism, and said rack rests on these tracks 80 until engaged by the lugs 59 of 'the lower horizontal conveyor. The lower conveyor then carries the racks to the right as viewed in Figure 1 and deposits them in succession on the tracks 8-101. carriages 32 verticallyslidably-mounted in stationary upbeat bases beat guides 38.

Driving mechanism for vertically "reciprocating the carriages 82 in the upbeat fer a rack from the lower conveyor to the unbcat guides, is best illustrated in Figures '9 through 15. These driving'means comprise pairs-of carriage rollers 84 turnably mountedon shafts '65 in the-carriages "8'2 and base rollers fifimounted on shafts 8'7 turnably supportcd inbeai ings 83 mounted at the bottom of the upbeat bases 83. As best seen in Figures ll through 15, "the rollers are 50 arranged that a pair of the carriage rollers 84 anda single base roller 86 are disposed substantially beneath each column of rack rollers A horizontally reciprocating wedge member -53 is disposed between the pairs of carriage rollers'oneach-can riage fiZ'and the base rollers 66. :liac'h wedge member 89 has central depending wedge portions 9i) which bear on thc'upiper surfaces of the base rollcrs 3". andsp'accd upstanding side wedge portions '91 which 'bear "against the lower surfaces of the carriagerollers 84. The rearward end of each wedge member 89 is :pivotally -connected to the forward end of a link 92 having its rearward end pivotally connected to a bran-K93 on as haft 94 journalled in a bearing member 95. The -sl1a'ft94 is rotated as indicated by arrows in Figure it) by means of an endless sprocket chain 96passing over a-sprocket wheel 97 on shaft'94 and -ovcr a sprocket wheel 98bit the main drive shaft '56. it will be seen that as the wedge members 89 are horizontally reciprocated they intermittently separate the carriage rollers =84 and the base rollers'86 thus intermittentlyelevating thecarriages 32 and the rack carried thereby from their :lowered .positions seen in Figures 11 and 13 to their raised positions seen in Figures 12 and 14. During this raising move ment the rack rollers 40 press inwardly and pass freely by latch rollers 99 onlatches 100 (see Figure "9) pivoted on the lower ends of the upbeat guides38. -When the rack rollers 40 have been elevated by the carriages "82 pastthe latch rollers 99, the latches 100 are moved "by the tension spring 101 to latching :position beneath the rack rollers 40'and this lowermost rack is thus suspended 83 located beneath 't'he upbases to thus intermittently trans- 40 on the upbeat guides.

on the latch members until moved farther upwardly and into the upbeat column by the next ascending rack.

The upbeat column of racks is actually supported by Geneva escapement mechanism similar to the downbeat escapement mechanism previously described but operated reversely thereto. This upbeat escapement mechanism comprises slotted Geneva wheels 102 mounted on shafts 103 journalled in brackets 104 secured to the frame of the structure, and escapement discs 105 having pins 106 mounted on shafts 107 journalled in the brackets 104. As best indicated in Figure l, the downbeat escapernent discs 74 and the upbeat escapement discs 105 on the same side of the apparatus are all driven by the same endless sprocket chain 108 which passes over a sprocket Wheel 109 on the main drive shaft 56, thence under and over sprocket wheels 110 respectively on shafts 75, thence over and under sprocket wheels 111 (see Figure 9) respectively on shafts 107, and finally returning to the main drive shaft 56 via idler sprockets 112 which may be vertically adjustably mounted on the frame 20 so that the chain 108 may be properly tensioned.

It will be seen that the sheet-drying racks 39 are, by the mechanism hereinbefore described, constantly circulated in a counter-clockwise direction as seen in Figure 1 through the drying chamber with an intermittent clocklike motion. Means are provided for feeding the coated sheets onto the racks within the chamber and for taking them off when dry. These means comprise a feed conveyor 113 and a take-off conveyor 114, both conveyors being indicated more-r-less diagrammatically in Figure 1. The feed conveyor 113 is desirably connected directly to the silk screen stencilling machine (not shown) so that the coated sheets 115 are automatically fed directly to the drying apparatus after coating. Also indicated in Figure 1 is a spray conduit 116 mounted by means of a bracket 117 on the dryer above the take-off conveyor 114, through which conduit 116 a fine powder may be sprayed onto the finished sheet stock as it emerges from the dryer. This is an added precaution against the sheets adhering to one another when they are removed from the take-off conveyor and placed in piles.

Explosive fumes from the drying paint on the coated sheets are normally removed from the drying chamber and it is desirable that the blower exhaust such fumes into the open air outside the building in which the drying apparatus is housed. However, precautionary measures are taken to prevent explosion within the chamber which might be caused by failure of the blower, or by sparks, etc. These safety means are shown diagrammatically in Figures 1 and 16, and comprise a tank 118 filled with a fire extinguishing agent such as CO: gas under pressure. A conduit 119 leads from the tank 118 to a valve 120, and other conduits 121 and 122 lead from the valve 120 to the upper and lower regions respectively of the drying chamber 22. The valve 120 is automatically opened to admit a sudden rush of the CO2 gas to the drying chamber whenever the pressure with the air-conditioning chamber 24 (which communicates with the drying chamber 22) rises only slightly above normal thus indicating the commencement of expansion of the gas within the chambers. The electric switch 123 which energizes mechanism to thus open the valve 120 when necessary, is automatically closed by a flexible diaphragm 124 mounted in the rear wall of the air-conditioning chamber 24 and operatively connected to the switch 123. It will thus be seen that a slight increase in pressure within the chamber will op crate to release the CO2 gas to the chamber. As an added precaution the top plate 21a for the drying chamber may be hingedly mounted as at 125 to the frame so that if an explosion should occur the expanding gases will blow the top or cover plate 210 open and thus escape instead of exploding the entire apparatus.

It may be found desirable to supply the power to the min drive shaft 56 of the rack-moving apparatus, through sprocket wheels 126 and chains 12') leading from the stencilling machine so that the stencilling machine and the drying apparatus are synchronized.

Figure 17 illustrates diagrammatically how the ca- It will thus be seen that the invention provides a sheet stock drying apparatus which is suitable for drying any sheet stock coated with any slow-drying paint, that the toxic paint odors from the drying the coated sheets are made to lie flat during drying thus permitting a wide range of materials, and that the apparatus shown and described is space-saving, efficient in operation, and reasonably economical in manufacture.

While but several specific embodiments of the invention have been herein shown and dc cribed, it will be understood that numerous details may be altered or omitted without departing from the spirit of the invention as' the same is defined by the following claims.

I claim:

1. Apparatus for drying coated sheet stock comprising:

guides and operable synchronously to intermittently deposit the lowermost rack onto the conveyor while sup-' thereabove; and driving means associguides for intermita rack from the conveyor to the upporting the racks tently transferring beat guides.

2. Apparatus for drying coated sheet stock comprising: a chamber; means for circulating air through the chamber; spaced vertical guides at opposite sides of the chamber arranged to provide a pair of opposite parallel downbeat guides and a pair of opposite parallel upbeat guides; a plurality of sheet-carrying racks having means on opposite sides thereof engageable with said pairs of guides may descend on the downbeat guides chronously to intermittently deposit the lowermost rack onto the conveyor while supporting the racks thereabove; and driving means associated with the bottom of the upbeat guides for intermittently transferring a rack from the conveyor to the upbeat guides.

3. Apparatus for drying coated sheet stock comprising: a chamber; means for circulating air through the chamber; means for conditioning the air circulated through the chamber so as to produce an atmosphere conducive to drying the coated sheets; spaced vertical guides at opposite sides of the chamber arranged to provide a pair of opposite parallel downbeat guides and a pair of opposite parallel upbeat guides; a plurality of sheet-carrying racks having means on opposite sides thereof engageable with said pairs .of guides whereby the racks may descend on the downbeat guides and ascend on the upbeatguides; a conveyor for transferring the racks from the bottom of vthe adow-nbeat guides to the bottom of the upbeat guides; Geneva escapement mechanism associated with the opposite sides of the lowermost rack on the downbeat guides and operable synchronously to intermittently deposit the lowermost rack onto the conveyor while supporting the racks thereabove; and driving means associated with the bottom of the upbeat guides for intermittently transferring a rack from the conveyor to the upbeat guides.

4. Apparatus for drying coated sheet stock comprising: spaced vertical guides arranged to provide a pair of opposite parallel downbeat guides and a pair of opposite parallel upbeat guides, each guide-comprising a channel barproviding front and rear vertical tracks; a plurality of sheet-carrying racks having pairs of rollers on-opposite sides thereof adapted to travel along the front and rear tracks respectively of said pairs of guides whereby the racks may descend on the downbeat guides and ascend on the upbeat guides; a conveyor for transferring the racks from the bottom of the downbeat guides to the bottom of the upbeat guides; Geneva escapement mechanism associated with the opposite sides of the lowermost rack on the downbeat guides and operable synchronously to intermittently deposit the lowermost rack onto the conveyor while supporting the racks thereabove; and driving means associated with the bottom-of the upbeat guides for intermittently transferring a rack from the conveyor to the upbeat guides.

5. Apparatus for drying coated sheet stock comprising: spaced vertical guides arranged to provide a pair of opposite parallel downbeat guides and a pair of opposite parallel upbeat guides, each guide comprising a channel bar providing front and rear vertical tracks; a plurality of sheet-carrying racks having pairs of rollers on opposite sides thereof adapted to travel along the front and rear tracks respectively of said pairs of guides whereby the racks may descend on the downbeat guides and ascend on the upbeat guides, the racks on the downbeat guides forming a column extending from the top to the bottom of the guides and with the rollers of each rack resting on the rollers of the rack therebelow; a conveyor beneath the lower ends of the guides for transferring'thc racks from beneath the downbeat guides to a position beneath the upbeat guides; Geneva escapement mechanism associated with the rollers on the lowermostrackon the downbeat guides and operable synchronously to intermittently deposit the lowermost rack onto the conveyor while supporting the column of racks thereabove; and driving means beneath the upbeat guides for intermittently transferring a rack from the conveyor to the upbeat guides.

6. Apparatus for drying coated sheet stock comprising: spaced vertical guides arranged to provide a-pair of opposite parallel downbeat guides and a pair of opposite parallel upbeat guides, each guide comprising a channel bar providing front and rear vertical tracks; a plurality of-sheet-carrying racks having pairs of rollers on opposite sides thereof adapted to travel along the front and rear tracks respectively of said pairs of guides whereby the racks :may descend on the downbeat guides and ascend on the upheatguides, the racks on the downbeat guides forming a column extending from the top to the bottom of the guides and with the rollers of each rack resting on the-rollers-of the rack therebelow; a conveyor beneath the lower ends of the guides for transferring the racks from beneath the downbeat guides to a position beneath the-upbeat guides; Geneva escapement mechanism associated with the rollers on the lowermost rack on the downbeatv guides and operable synchronously to intermittently deposit the lowermost rack into the conveyor while supporting the column-of racks thereabove; driving means beneath the upbeat guides for intermittently transferring a rack fnomithe conveyor to the upbeat guides; and :Geneva escapement mechanism associated with the rollers of (the lowermost rack on the upbeat guides and operable synchronously to receive a rack from said driving means while supporting the column of racks thereabove.

7. Apparatus for spaced vertical guides arranged to provide a pair of opposite parallel downbeat guides and a pair of opposite parallel upbeat guides; a plurality of sheet-carrying racks having means on opposite sides thereof'engageable with said pairs of guides whereby the racks may descend-on the downbeat guides and ascend .on the upbeat guidesya conveyor for transferring the racks from the bottom of the-downbeat guides to the bottom .of the upbeat guides;

and reciprocating wedges beneath the upbeat .guidesfor intermittently transferring va rack from the conveyor to the upbeat guides. t

Apparatus for drying coated sheet stock comprising: spaced vertical guides arranged to provide a pair of vopposite parallel downbeat guides and a pair =ofopposite parallel upbeat guides, each guidecomprising a channel bar providing front and rear vertical tracks; a plurality of sheet-carrying racks having pairs of rollers on opposite sides thereof adapted to travel along the front and rear tracks respectively of said pairs of guides whereby the racks may descend on the downbeat guides and ascend on theupbeat guides, the racks on the guides forming a downbeat column and an upbeat column both extending from top to bottom of the guides and with the rollers of each rack resting on the rollers of the rack therebelow; a conveyor for transferringthe racks from the bottom of the downbeatgu'ides to the bottom of the upbeat guides; a pair of carriages beneath the upbeat guides adapted to receive successive racks from the conveyor, said carriages eachhaving a way for accommodating the pair of rollers on the adjacent side of each rack; and driving means beneath thecarriages for vertically reciprocating the carriages'to intermittently elevate a rack to the upbeat guides, said driving means comprising a stationary base beneath each carriage having horizontally spaced rollers beneath the rollers on the racks in the upbeat column, horizontally spaced rollers on each carriage above the rollers on the base, and a horizontally reciprocating wedge member having wedge portions travelling on the base rollers and supporting the carriage rollers whereby reciprocating movement of the wedge members effects raising and lowering movements of the carriages.

9. Apparatus for drying coated sheet stock comprising: spaced vertical guides arranged to provide a pair of 0pposite parallel downbeat guides and a 'pair of opposite parallel upbeat guides; a plurality -of sheet-carrying racks having means on opposite sides thereof engageable with said pairs of'guides whereby the racks may descend on the downbeat guides and ascend on the upbeat guides, said racks each having a pair of laterally spaced depending fingers thereon; a conveyor for"transferring the racks from the bottom of the downbeat guides to the bottom of the upbeat guides, said'conveyor comprising'two pairs of laterally spaced'horizontally disposed sprocket chains having lugs "thereon adapted to engage the depending fingers on the racks and a'.pause station'between the downbeat guides and the upbeat guides, the lugs on the first pair of chains engaging said pair of depending fingers on each rack to move said rack to the pause station and the lugs onthe second pair of "chains thereafter engaging said pair of fingers on said rack to move .the rack to a position beneath the upbeat guides; and driving means associated with the bottom of the upbeat guides for intermittently transferring a rack from the secondpair of chains to the upbeat guides while the succeeding rack pausesat said pause station.

10. Apparatus for drying coated sheet stock comprising: spaced vertical guides arranged 'to provide ajpair of opposite parallel downbeat guides and a-pair of opposite parallel upbeat gguides; a plurality of sheebcarrydrying coated sheet stock comprising;

ing racks having means on opposite sides thereof engageable with said pairs of guides whereby the racks may descend on the downbeat guides and ascend on the upbeat guides; a lower conveyor for transferring the tom of the upbeat guides; Geneva escapement mechanism the opposite sides of the lowermost rack on the downbeat guides and operable synchronously to intermittently deposit the lowermost rack onto the conveyor while supporting the racks the top of the upbeat guides to the top of the downbeat guides.

11. Apparatus for drying coated sheet stock comprising: a chamber; means for circulating air through the chamber; spaced vertical guides at opposite sides of the chamber arranged to provide a pair of opposite parallel downbeat guides and a pair of opposite parallel upbeat guides; a plurality of sheet-carrying racks having means on opposite sides thereof engageable with said pairs of guides whereby the racks may descend on the downbeat guides and ascend on the upbeat guides, said racks each of a frame having slats mounted spacedly a conveyor for transferring the racks from the bottom of the downbeat guides to the bottom of the upbeat guides; Geneva escapement mechanism associated with the opposite sides of the lowermost rack on the downbeat guides and operable synchronously to intermittently deposit the lowermost rack onto the conveyor while supporting the racks thereabove; and driving means associated with the bottom of the upbeat guides for intermittently transferring a rack from the conveyor to the upbeat guides.

References Cited in the file of this patent UNITED STATES PATENTS 1,037,075 Spurrier Aug. 27, 1912 1,089,944 Muller Mar. 10, 1914 1,625,086 Matushita Apr. 19, 1927 1,784,727 Harris Dec. 9, 1930 1,846,258 Johnson Feb. 23, 1932 1,946,923 Wilcox Feb. 13, 1934 2,127,217 Von Heinrich Aug. 16, 1938 2,136,880 Honigman Nov. 15, 1938 2,303,809 Anderson Dec. 1, 1942 2,530,001 Cowan Nov. 14, 1950 FOREIGN PATENTS 61,702 Denmark Nov. 29, 1943 

1. APPARATUS FOR DRYING COATED SHEET STOCK COMPRISING: SPACED VERTICAL GUIDED ARRANGED TO PRODUCE A PAIR OF OPPOSITE PARALLEL DOWNHEAT GUIDES AND A PAIR OF OPPOSITE PARALLEL UPHEAT GUIDES; A PLURALITY OF SHEET-CARRYING RACKS HAVING MEANS ON OPPOSITE SIDES THEREOF ENGAGEABLE WITH SAID PAIRS OF GUIDES WHEREBY THE RACKS MAY DESCEND ON THE DOWNBEAT GUIDES AND ASCEND ON THE UPBEAT GUIDES; A CONVEYOR FOR TRANSFERRING THE RACKS FROM THE BOTTOM OF THE DOWNBEAT GUIDES TO THE BOTTOM OF THE UPBEAT GUIDES; GENEVA ESCAPEMENT MECHANISM ASSOCIATED WITH THE OPPOSITE SIDES OF THE LOWERMOST RACK ON THE DOWNBEAT GUIDES AND OPERABLE SYNCHRONOUSLY TO INTERMITTENTLY DEPOSIT THE LOWERMOST RACK ONTO THE CONVEYOR WHILE SUPPORTING THE RACKS THEREABOVE; AND DRIVING MEANS ASSOCIATED WITH THE BOTTOM OF THE UPBEAT GUIDES FOR INTEMITTENTLY TRANSFERRING A RACK FROM THE CONVEYOR TO THE UPBEAT GUIDES. 